1. Field of the Invention
This invention relates to a vehicle driving support apparatus mounted on a vehicle, for performing automatic following control for following a leading vehicle ahead of the own vehicle, detected with a stereo camera, a mono camera, or a millimeter wave radar or the like.
2. Description of Related Art
In recent years, travel control systems have been practical used. In these systems have a camera or the like for detecting the travel environment ahead of the vehicle, and for detecting a leading vehicle (front vehicle) based on this travel environment data. According to the detected front vehicle, the systems perform travel control for following the front vehicle and/or keeping the inter-vehicle distance to the front vehicle above a fixed distance.
For example, Japanese unexamined patent publication 5-104977, a vehicle travel control apparatus is disclosed which computes an estimated safe inter-vehicle distance as of after an estimation time elapses, predetermined on the basis of a vehicle speed, a relative speed and an acceleration, or decided using fuzzy logic; computes an estimated inter-vehicle distance as of after the estimation time elapses, on the basis of an inter-vehicle distance and a relative speed; and computes a target vehicle speed on the basis of this estimated inter-vehicle distance and estimated safe inter-vehicle distance.
However, in the above-mentioned patent publication, an estimation time used as an initial reference is just set as a fixed value decided from the weight or natural frequency or engine torque of the own vehicle, or a function of an acceleration and a speed and/or relative speed, and because the present positional relationship with the front vehicle is not taken into account, there is the problem that in some cases the estimation time is set too long and the own vehicle comes too close to the front vehicle, or the estimation time is set too short and smooth control is not possible.